Theodore berdell



T. BERDELL.

(No Model.)

TELEPHONE.

No. 559,988. Patented May 12, 1896.

AN DREW B GBMAM. PHDTO-Lm-ICL WASHIN Gran. D c.

- UNITED STATES PATENT OFFICE.

THEODORE BERDELL, OF NEIV YORK, N. Y.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 559,988, dated May 12,1896.

Application filed March 8, 1895. Serial No. 540,982. (No model.)

To aZZ whom, it may concern:

Be it known that I, THEODORE BERDELL, a citizen of the United States,residing in the city, county, and State of New York, have invented a newand useful Improvement in Telephones, of which the following is aspecification.

My invention relates to telephones, particularly to such as are employedfor transmitting articulate speech, and has for its object the provisionof a telephone simple in construct-ion and very sensitive to sound.

My invention consists, essentially, in locating the diaphragm in amagnetic field in a position of stable magnetic equilibrium or positionof magnetic equipoise as contradistinguished from an unstable positionor position of magnetic bias. hen mounted in accordance with myinvention, the movement or vibrations of the diaphragm in eitherdirection away from normal position are in such direction with referenceto the lines of magnetic force that it will be restored by the magneticforces to the normal position.

My invention further consists in mounting a diaphragm which is unsecuredor free to vibrate at its edges in a magnetic field in a position ofstable magnetic equilibrium. \Vhen such a diaphragm is so mounted in amagnetic field and properly guided, it is practically fioated in themagnetic field.

I11 carrying out my invention the diaphragm, which is of magneticmaterial, as well understood in the art, may be placed in the magneticfield or lines of force joining two poles either of the same or separatemagnets, its plane being practically coincident with or parallel to saidlines, or the field in which it is placed may be produced by the singlepole of a magnet. In either case the direction of vibration of thediaphragm would practically be transverse to the lines of force or insuch direction as to tend to carry the diaphragm from a stronger to aweaker field, whereby it would be restored or drawn back to the centralor normal position, which is the position of magnetic equipoise. I donot, however, limit myself to the number or special disposition of themagnetic poles or form or special direction of lines of force withreference to the diaphragm, as any mounting of the diaphragm in aposition of magnetic equipoise or equilibrium in a magnetic field wouldbe within my invention.

My invention also consists in certain other novel and usefulcombinations or arrangements of parts and peculiarities of constructionand operation, all of which will be hereinafter first fully described,and then pointed out in the claims.

In the accompanying drawings, forming a part hereof, Figure 1 is alongitudinal vertical sectional view of a telephone embodying myinvention, taken at line a a of Fig. 2. Fig. 2 is a verticalcross-sectional view at line x x of Fig. l, and Fig. 3 is a like View atline y 1 of the same figure. Fig. 4 shows the, diaphragm as locatedbetween the poles of two separate magnets, and Fig. 5 as opposite thepole of a single magnet.

Similar numerals of reference wherever they occur indicate correspondingparts in all the figures.

I will first describe my invention as carried out with ahorseshoe-magnet, which, for illustration only, is shown and describedas a permanent magnet.

1 is such a magnet. Between the two poles of the magnet is a box or case2, of any approved insulating material, having an opening 3 at its frontfor the admission of sound.

is a diaphragm of soft iron, preferably free at its edges and guided insaid case in anysuitable way. The diaphragm, as shown, is located in themagnetic field between the two poles of the magnet, and its plane ispractically coincident with the direction of the lines of force joiningsaid poles. The proper position may be practically determined byallowing the diaphragm to move in the space between the poles in adirection at right angles to the line joining said poles until it findsits position of rest or equilibrium, which, as is well known, would bejust back of the ends of the poles and in the strongest portion of thefield between them. If moved from this position in either direction in aline transverse to a line joining the poles, the magnetic forces wouldrestore it to the normal position. I have found that a diaphragm somounted is very sensitive to sound-waves, particularly to such as areproduced by articulate speech. A diaphragm so mounted and arranged in amagnetic field is practically floated in a magnetic field, being keptout of contact with the 'magnet and being so floated without anymechanical clamping or holding devices at its edge is particularly freeto respond to sound Vibrations.

IVhen the diaphragm operates upon electrodes, the latter arepreferablymounted and supported as follows: Placed across the case 2 arepencils or cylinders 4, preferably of carbon, forming one of theelectrodes of the telephone. These pencils are yieldingly supported attheir ends by being held in (himbles of rubber or equivalent yieldingmaterial 5. The pencils at are electrically connected at 6, and arealsoelectrically connected to a binding-post '7, fixed in the case Thebinding post 8 is connected with the diaphragm or the electrode thereon.Attached to the rear of the diaphragm is a carbon electrode 11, whichbears against the pencils 4. By the peculiar arrangement of yieldingsupports for the ends of the electrodeseall buzzing or snapping soundsare eliminated, while ample provision is made for the requisiteyibration.

The parts of my telephone may be mounted and inclosed in any convenientcase when in use.

I have particularly illustrated my invention as employing a magnet ofthe horseshoe type; but two separate magnets may be used, or a singlemagnet,tl1e results being practically the same. In Fi a the diaphragm 10is shown supported upon a non-magnetic piece 12, between the poles 1 ofseparate magnets, and in Fig. 5 but a single magnet placed above thediaphragm is used. In all these cases the diaphragm occupies a positionof magnetic equilibrium, so far as concerns vibrations of the same inresponse to sound-waves.

That I claim as my invention is- 1. In a telephone, a diaphragm mountedin a magnetic field in a position of magnetic equipoise or stableequilibrium, as and for the purpose described.

In a telephone, a diaphragm free at its edges and floated in a magneticfield, as and for the purpose described.

3. In atelephone, the combination,substantially as described, with adiaphragm free at its edges, of a guiding-case therefor, and a magnet ormagnets in the field of which the diaphragm floats, as and for thepurpose described.

4. In a telephone instrument, the combination, with a horseshoe-magnet,of a diaphragm floated in a position of magnetic equipoise in the fieldbetween the poles of said magnet, and an electrode or electrodes uponwhich the diaphragm operates, substantially as and for the purpose setforth.

5. In a telephone instrument, the combina tion with aninsulating-support, of an electrode yieldingly mounted therein, amagnet, and a diaphragm loosely resting upon said electrode and mountedin a position of magnetic equilibrium between the poles of said magnet.

6. In a telephone instrument, a suitable support, a magnet, and anelectrode formed of cylinders of carbon mounted at their ends inyielding rings within the support, in combination with a diaphragmresting upon said cylinders and loosely held in place with its planeparallel to the lines of force joining the poles of said magnet,substantially as shown and described.

7. In a telephone instrument, a support, a magnet and a pair of carboncylinders yieldingly mounted within the support and forming anelectrode, in combination with a diaphragm loosely held in place in orabout the position of magnetic equipoise in the field of force of saidmagnet and bearing an electrode, as and for the purpose described.

THEODORE BERDELL. V itnesses:

A. M. PIERCE, E. D. \VRIGHT.

